Water / Wastewater Treatment Electro-Coagulation Treats Water in Holland


With ever increasing demands to minimise pollutants in water effluent arising from industrial processes, Aquaco water recycling (UK) can offer a solution which works well in many industries.


This is the Red Box Electro Coagulation system whereby contaminants are flocculated by an electrical process into a size which can then be filtered, pressed and disposed of. The flocculation process in the reactor is based on electrolysis. When the installation is switched on, air is blown through the water in the reactor vessel. This is to keep the water in motion and to prevent solids sinking to the bottom. Every thirty seconds an extra boost of “cleaning-air” is blown through the water.


The contaminated water flows from the reactor into the electro-coagulation or flocculation vessel. In this vessel there are three level sensors which control water levels and pumps. In a typical system, the reactor contains Fe- (iron) and Al- (aluminium) electrodes, although other types of electrodes can solve different problems . Four of them are connected to the anode (+) and the other four are connected to the cathode (-). The voltage-level varies between nine and eleven Volts.


The Fe- and Al- electrodes connected to the anode are slowly converted into Fe203 and AL2(0H)3. The resulting roughly formed flocks provide a place for any contaminant in the water to attach to. The dissolved contamination is connected to the flocks and is transformed into non-dissolvable particles. These particles can easily be separated from the treated water by filtration. Above the flocculation vessel there is a sprinkler. The sprinkler controls the foam-level in the vessel. The system transfers the contaminant, now flocculated into large particles, and water mix in to a filter press


which is closed by a hand operated or automatic hydraulic system. The filter press allows the clear water to run to tank or drain while pressing the flocculated contaminant into a cake which is light and easily handled for disposal. A typical successful installation is at the large Forbo Novilon BV works in Eastern Holland. Forbo prints vinyl but the effluent to be treated would be similar to that of any printing works. The printing rollers are washed down with water and the waste has in the past then been passed though a membrane filter. The concentration of ink in the water would vary depending on the amount of water


used in the wash down process by a particular operative. The membrane filter tended to become blocked by the ink and needed regular maintenance at a significant cost to meet the regulations for disposal of effluent. The flow rate required was 4 cubic meters per


day or 200 litres per hour, which involved the use of one large Red Box to treat the water by electro- coagulation. As the concentration of ink is high from the wash down process, the effluent is diluted by 4 times before treatment by recycling clean output water from the system back into the raw effluent.


Effluent is stored in a pre-treatment tank from where it is pumped into the reactor tank at the required rate by the control panel in the Red Box. pH is important to the process and, where required, a separate pH corrector tank can be installed, also controlled by the Red Box. Voltage and current are run across the electrodes in the reactor vessel.


They are controlled by the transformer and rectifier in the Red Box. The system automatically adds brine to the reactor vessel to increase conductivity as required. The chemical process takes place in one half of the reactor vessel while the other half acts as a settlement tank before the coagulated contaminants and water are pumped at a controlled rate to the filter press. The filter press is operated automatically. The clear water runs away to drain whilst the coagulated contaminants are left in the filter cloths in the press forming a cake.


When the press is full, it is opened releasing the pressure and the cake is removed and taken away for disposal. Aquaco will process a sample of effluent at no charge to demonstrate the suitability of the system for a particular site. Aquaco can then supply a trial Red Box system on a rental basis to run at a customer’s plant prior to any capital investment in a new system. Typical industries where the Red Box has resolved effluent problems include transport (vehicle wash down), surface treatment, textile, printing, chemical and waste disposal.


Reader Reply Card No 27


Maximising Biogas Production in the Food and Beverage Industries


BG Max from Novozymes (France) maximises biogas potential while improving the efficiency of anaerobic systems in wastewater treatment operations in the food and beverage industries. A biological formulation that combines beneficial microorganisms and fast-acting enzymes, BG Max dramatically increases the conversion of COD into volatile fatty acids, initiating methane production. Meanwhile, the specially selected enzymes in the formulation kick- start the metabolism of proteins and starches as well as enhance the hydrolysis of fats. Sludge quantity and treatment costs are reduced, while waste is turned into energy, increasing the return on investment.


“BG Max is another great innovation from Novozymes that helps our customers get the most out of their anaerobic wastewater


system,” explains Global Marketing Manager Chris Day. “With this product our customers can more efficiently transform wastewater into valuable energy while reducing the overall cost of treatment.” sludge reduction in municipal and pulp & paper lagoons.


Reader Reply Card No 28


UV Disinfection for Canadian Drinking Water Plant


WEDECO UV reactors at Seymour-Capilano Filtration Plant save on costs and ensure proper disinfection for new facility. With a capacity to treat up to 1.8 billion litres per day of water, the largest ultraviolet (UV) disinfection facility for drinking water in the world – the Seymour-Capilano Filtration Plant – became fully operational earlier this year with UV disinfection reactions from ITT Corporation at its core. ITT supplied 24 of its WEDECO K 143 Series UV light disinfection reactors to the state-of-the-art plant, which was completed in time for the 2010 Winter Olympics held in the Vancouver area in February, and celebrated during a ceremony in the second quarter.


Mobile Sludge Dewatering Riga


Sludge dewatering specialists, Alfa Laval (UK), have recently converted a standard ISO container into a mobile dewatering rig for trial and test purposes.


Equipped with the latest Alfa Laval decanter centrifuge technology, the mobile rig is capable of dewatering 40 cubic metres of sewage sludge per hour. It comes equipped with its own diesel-powered generator and an integral liquid polymer make-up system. It can also be adapted to work with powder polymer for short periods for test purposes and can also be wired into a 160 amps mains supply, if required, for a longer period. An on-board, retractable screw conveyor transports the dried sludge into a feed hopper or main conveyor system.


Since the container is completely self-contained, all the sewage treatment works needs to supply is the sludge for treatment, diesel for the generator, potable water for polymer make-up and final effluent for polymer dilution and wash water.


Reader Reply Card No 29 ITT was chosen in late 2004 to introduce UV disinfection


technology to the plant based largely on a much lower life cycle cost of the WEDECO system over competing brands. This included operation and maintenance as well as energy efficiency savings. The WEDECO system uses approximately two-thirds less energy than comparable medium pressure UV systems.


"Each reactor has a capacity of about 20 million gallons per


day (MGD). Every reactor has exactly 48 lamps in four rows of 12, with additional space for a fifth row for future expansion,“ said Paul Donnini, managing director for ITT’s Water & Wastewater business in Canada. Validated according to U.S. Environmental Protection Agency guidelines, the WEDECO K Series of UV reactors are for large flow drinking water applications. The WEDECO Spektrotherm®


lamps are powered


by the latest electronic ballast technology designed specifically for this lamp and controlled by a highly selective calibrated UV intensity sensor that allows for significantly lower energy costs. It also decreases the overall chemical use in drinking water.


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Located in the Greater Vancouver Regional District (GVRD) of British Columbia, the facility draws its water from the Seymour and Capilano reservoirs. Along with the Coquitlam Reservoir – all fed by namesake mountain watersheds north of Vancouver – these reservoirs supply the water for 2 million residents in the region. About 70 percent of the area‘s drinking water needs are met by the Seymour and Capilano watersheds.


Reader Reply Card No 30


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